experimental verification of joule's law of heating class 10

Joules law of heating equation

state joule’s law of heating.

“The heat produced in a conductor is: (1) Directly proportion the square of current passing through the conductor,(H ∝ I²) keeping R and t constant; (2) Directly proportion to the resistance of the conductor (H ∝ R) keeping I and t constant; and (3)Directly proportional to the time of flow of current (H ∝ t) keeping I and R constant.”

joules law of heating formula

Verification of joule’s law:.

The above laws of heating by the electric current can be verified in the laboratory using a joule’s calorimeter. To verify the above laws, heat is generated in a resist; coil R which is enclosed in a copper calorimeter containing water to about two-thirds of its volume. The ends of R are connected to finding terminals fixed to the lid. The calorimeter is enclosed in a wooden box to minimize the logs of heat. A is the ammeter to measure the current and V is the voltmeter to measure the potential difference across R. A rheostat is connected in the circuit to alter the current.

(a): Let W be the total water equivalent of the calorimeter (including the calorimeter, stirrer, and water ) and T1 the initial temperature. A current of I1 amperes is passed for a known interval of time (about 15 to 20 minutes) and the final temperature T2 (after correcting for the loss of heat by radiation ) is noted. Then, the quantity of heat produced =HI=W[θ1 -θ2]. Similarly, the experiment is repeated with different values of current I2,I3, etc.( after cooling the calorimeter to the initial temperature) and the corresponding quantities of heat produced H2, H3, etc are noted, keeping R and t constant.

Joules law derivation

Applications of heating effect of current.

1: Safety fuse : A safety fuse is a short piece of wire with a low melting point. This is made of an alloy of tin and lead. The fuse wire is connected in series with the electrical installation and, when the current in the circuit exceeds the rated value, the fuse wire gets heated to a temperature higher than its melting point. The wire melts and the electric circuit is cut off. The temperature to which the wire gets heated is directly proportional to the cube of the radius. Thus the temperature depends only on the current flowing through the wire and its radius irrespective of its length.

2:Electric heater or stove, electric Radiators, and electric Iron. All these are based on the same principle that is produced when electric current flows through a wire. These contain coils of nichrome (an alloy of nickel and chromium) and large currents of the order of 3 to 5 amperes can be passed through them. In the case of an electric heater working 220 volts and consuming a power of 1000 watts, the current through the coils will be 4.55 amperes. The resistance of the coil will be 48.4 ohms. In the case of electric radiators, the coil is placed along the axis of a parabolic metallic reflector or at the focus of a concave reflector.

Seebeck effect

If two metal wires or strips A and B made of dissimilar metals are joined at the ends to form two junctions shown in the figure, then such a device is called a thermocouple. If two junctions of a thermocouple are kept at different temperatures, an electric current will be induced in the loop. This effect is called the Seebeck effect, and emf so developed is known as Seebeck emf or Thermo emf. The magnitude and direction of the emf depend upon the metals used and the temperature difference between hot and cold junctions. The Thermo emf induced is given by:

E = αμ + βθ²/2

Note that curve is parabolic. Note that natural temperature Remains unchanged when temperature of cold junction is curved.

At neutral temperature emf is maximum.

Peltier effect

The converse of Seebeck effect is Peltier effect. If current is passed through a thermocouple or an external battery is applied across the two junctions of a thermocouple then one of the junctions becomes hot and other gets cold. The heat liberated or absorbed at one of the junctions is given by: ΔH/ΔQ=πAB ,Which is Peltier emf.Where ΔQ is charge transferred. Peltier coefficient is the amount of heat liberated per second when 1-A of current is passed through a thermocouple.

Thomson effect

Applications of thermal effects of current

Electro power generation
Refrigeration
Detection and heat radiation
Measurement of temperature

What is ohm’s law class 10, combination of capacitance in series and parallel circuit, maxwell’s equations: derivation in integral and differential form, electromagnetism examples, leave a reply cancel reply.

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed .

PDF chapter test TRY NOW

Science CBSE
Electricity
Electric circuits - Components, effects and applications

20. Joule's law of heating

Heating Effect Of Electric Current

Introduction to the Heating Effect of Electric Current

Whenever electric current flows through a conductor, the conductor heats up due to the collisions between the free-flowing electrons and the atoms of the conductor. This phenomenon is known as the heating effect of electric current. The electrical energy supplied by the current is converted into heat energy, which can be observed in everyday appliances like electric irons, heaters, and filament bulbs.

This effect plays a significant role in both useful applications (like electric heaters) and potential hazards (like overheating of electrical circuits). Understanding the heating effect of electric current helps in designing devices and circuits that efficiently convert electrical energy into heat or prevent overheating in undesired situations.

Joule’s Law of Heating

The heat produced in a conductor due to the flow of electric current is governed by Joule’s Law of Heating, which states that the amount of heat produced (H) in a conductor is directly proportional to:

Mathematically, Joule’s Law is expressed as:

This equation shows that the heat produced is proportional to the square of the current, meaning even a small increase in current results in a large increase in heat.

Derivation of the Heat Formula

The heat produced by an electric current can also be derived using the formula for electric power:

Thus, we obtain the formula for the heat generated:

Applications of the Heating Effect of Electric Current

The heating effect of electric current is widely used in various appliances and devices, where electrical energy is deliberately converted into heat energy. Some common applications include:

Electric Heaters: Electric heaters such as room heaters and water heaters use high-resistance wires (usually made of nichrome) to convert electrical energy into heat. When current flows through the high-resistance heating element, it generates heat, which is used to warm the surroundings or heat water.

Electric Iron: Electric irons use the heating effect to iron clothes. A high-resistance coil is embedded inside the iron, which heats up when current flows through it. The heat generated by the coil is then used to press clothes.

Electric Bulbs (Incandescent Lamps): Incandescent light bulbs work on the principle of the heating effect. When current flows through the thin tungsten filament, it heats up to a very high temperature, causing it to emit light.

Electric Fuses: Electric fuses protect electrical circuits from excessive current. When too much current flows through a circuit, the fuse wire (made of a material with low melting point) heats up and melts, breaking the circuit and preventing damage to electrical devices.

Electrical Energy and Power

The electrical power consumed by a resistor is given by:

Or alternatively, using Ohm’s Law:

The total electrical energy consumed over time is given by:

Factors Affecting the Heating Effect

Several factors influence the amount of heat produced when current flows through a conductor:

Practical Considerations and Safety Measures

While the heating effect of electric current is useful in many applications, it can also lead to overheating in electrical circuits, posing safety hazards. Here are some safety measures to avoid the harmful effects of excessive heating:

Use of Fuses and Circuit Breakers

Fuses and circuit breakers are safety devices that automatically break the circuit if the current exceeds a safe limit. This prevents excessive heating, which could cause fires or damage to appliances.

Proper Insulation

Conductors and wires should be properly insulated to prevent overheating and electrical shocks. Insulation prevents the loss of energy as heat and ensures that electrical energy is used efficiently.

Proper Ventilation

Electrical appliances that generate heat, such as computers and televisions, should be placed in well-ventilated areas to avoid the accumulation of heat. Poor ventilation can cause the devices to overheat and malfunction.

Appropriate Wiring

Electrical wiring in homes and buildings should be of the appropriate thickness and material. Wires with insufficient thickness can overheat and cause electrical fires.
Real-Life Applications of the Heating Effect

Room Heaters and Electric Kettles: Room heaters and electric kettles use nichrome wires, which have high resistance. When current passes through these wires, they generate heat, which is used to warm the room or boil water.

Filament Bulbs: Filament bulbs rely on the heating effect of current flowing through the tungsten filament. The filament heats up to a high temperature and emits light as a result.

Cooking Appliances: Devices like electric stoves and toasters utilize the heating effect of current. These appliances have heating elements that become hot when current flows through them, converting electrical energy into heat for cooking food.

Key Practice Questions

Q3: A 100 W bulb operates on a 220 V supply. Calculate the current flowing through the bulb and the resistance of its filament.

How does a fuse work using the heating effect of electric current?

A fuse works by using a thin wire with a low melting point. When excessive current flows through the fuse, the wire heats up due to the heating effect and melts, breaking the circuit and preventing damage to appliances.

What are some applications of the heating effect of electric current?

Applications of the heating effect include electric heaters, electric irons, toasters, fuses, and filament bulbs. These devices convert electrical energy into heat energy for useful purposes.

Why do electric appliances like heaters use high-resistance materials?

High-resistance materials, like nichrome, are used in electric heaters because they generate more heat when current flows through them. This is because the heat produced is directly proportional to the resistance of the material.

How is heat produced in a conductor related to current?

What is the heating effect of electric current.

The heating effect of electric current refers to the phenomenon where heat is generated when an electric current flows through a conductor. This occurs due to collisions between electrons and atoms in the conductor.

Related Topics
What is Hypothesis?
Work, Energy and Power
The Human Eye And The Colourful World
Resistance Of A System Of Resistors
Refraction Of Light Through A Prism
Refraction Of Light
Bernoullis Principle
List of Physics Scientists and Their Inventions
Circuit Diagram
Atmospheric Refraction
Acceleration
Physics FAQs
Full Wave Rectifier

Magnetic Field Due To A Current – Carrying Conductor
Magnetic Field And Field Lines
Magnetic Effects Of Electric Current
Factors On Which The Resistance Of A Conductor Depends
Electric Potential And Potential Difference
Electric Current And Circuit
Domestic Electric Circuits
Modern Periodic Table
Some Important Carbon Compounds – Ethanol And Ethanoic Acid
Soaps And Detergents
Versatile Nature Of Carbon
How Strong Are Acid Or Base Solutions?
Understanding the Chemical Properties of Acids and Bases
Acids, Bases, and Salts
Chemical Properties Of Carbon Compounds
Bonding In Carbon – The Covalent Bond
How Do Our Activities Affect The Environment?
Sexual Reproduction
What Are Life Processes?
Life Processes
Heredity Traits
Accumulation Of Variation During Reproduction
Modes Of Reproduction Used By Single Organisms
Do Organisms Create Exact Copies of Themselves?
Pair of Linear Equations in Two Variables
Relationship between Zeroes and Coefficients of a Polynomial
Introduction to Polynomials
Revisiting Irrational Numbers
The Fundamental Theorem of Arithmetic
Real Numbers
Pythagoras Theorem
Probability
Mensuration

Join deeksha vedantu, > pu + competitive exam coaching preferred choice for toppers 25+ years of academic excellence 70k+ success stories, related pages, competitive exams.

Young’s Double Slit Experiment
Semiconductors
Raoult’s Law
Heisenberg Uncertainty Principle
Electromagnetic Spectrum
Coulomb’s Law
Correlation Coefficient
Chemical Bonding
Binomial Theorem
Basic Logic Gates
Important Notes For NEET Biology – Chromosome Structure
Important Notes For NEET Biology – Cell Cycle and Cell Division
DNA Polymerases
Important Notes For NEET Biology -Shapes of Bacteria
Important Notes For NEET Biology – Morphology of Flowering Plants
Important Notes For NEET Biology – Breathing and Exchange of Gases

No pages found.

Latest Posts

Admission Enquires Open for 2024-25

A reputed name in the 11th & 12th and Competitive Exam Coaching space, Deeksha thrives on blending the best of technology and academics — while nurturing children in an environment that prioritises wellness and care. Deeksha’s expert pedagogy inspires confidence and original thinking by making learning fun and effective

Deeksha Campuses

Book a dSAT Slot

JEE Coaching

NEET Coaching

KCET Coaching

Results At Deeksha

PU Colleges In Bangalore

CBSE Sample Paper For Class 10

ICSE Sample Paper For Class 10

KSEEB Prev. Year QP For Class 10

Top Resources

Mathematics
JEE , NEET , KCET

Admissions Enquiries Open For 2025-26 | Pre University Results Out For 2024 | PU College in Bengaluru | Top PU College in Karnataka | Integrated PU Colleges | JEE Coaching | NEET Coaching | KCET Coaching | Admissions Enquiries Open For 2025-26 | Pre University Results Out For 2024 | PU College in Bengaluru | Top PU College in Karnataka | Integrated PU Colleges | JEE Coaching | NEET Coaching | KCET Coaching |

Head Office

Download class 10 mid term revision resources, fill the form below to continue.

Email Address*

Phone Number*

Class & Board of Child* —Please choose an option— 10th, CBSE 10th, ICSE 10th, State Board Other

Preferred Deeksha Campus* —Please choose an option— Deeksha Vedantu, Kanakapura Road, Bengaluru Deeksha Vedantu, Indiranagar, Bengaluru Deeksha Vedantu, Yelahanka, Bengaluru Deeksha Vedantu, Mahalakshmipuram, Bengaluru Vedantu Learning Centre, JP Nagar, Bengaluru Deeksha Vedantu, Kengeri, Bengaluru Deeksha Vedantu, Whitefield, Bengaluru Deeksha Vedantu, Main Campus, Bengaluru Deeksha Vedantu, Thyagarajanagar, Bengaluru Deeksha Vedantu, Thanisandra, Bengaluru Deeksha Vedantu, Vidyanagar, Bengaluru Deeksha Vedantu, Judicial Layout, Bengaluru Deeksha Vedantu, Excellence Batch, Bengaluru Deeksha Vedantu, Nelamangala Boys, Bengaluru Deeksha Vedantu, Nelamangala Girls, Bengaluru Deeksha Vedantu - ES, Somanahalli, Bengaluru Deeksha Vedantu - DSS, Bannerghatta Road, Bengaluru Deeksha Vedantu - AJPS, KR Puram, Bengaluru Deeksha Vedantu, NR Colony, Bengaluru Deeksha Vedantu, Electronic City, Bengaluru Deeksha Vedantu - NEC, Mathikere, Bengaluru Deeksha Vedantu, Bhughathalli, Mysuru Not Sure

I agree to the privacy policy and T&C

Admission Enquiries Open For 2025-26

Top PU college with integrated coaching for JEE, NEET, KCET & other competitive exams.

Take dSAT & get up to 90% scholarships. Limited Seats.

Please Fill The Form Below To Continue

Enter Your Details Below

Free download kseeb question papers, fill the form below to get your question paper bundle., kcet crash course enquiry form, limited seats available. batch starting soon.

Preferred KCET Campus* —Please choose an option— Deeksha Vedantu, Vidyanagar, Bengaluru(Residential/ Day Scholar Campus) Deeksha Vedantu, Mahalaxmipuram, Bengaluru(Day Scholar Campus) Not Sure

Preferred KCET Campus* —Please choose an option— Deeksha Vedantu, Vidyanagar ,Bengaluru(Residential/ Day Scholar Campus) Deeksha Vedantu, Mahalaxmipuram ,Bengaluru(Day Scholar Campus) Not Sure

Your Name*:

Your Email Address*:

Your Phone Number*:

Current Class & Board of Child*: —Please choose an option— 10th, CBSE 10th, ICSE 10th, State Board Other

Course Interested In*: —Please choose an option— 11th and 12th Foundations (8th - 10th) Other

Preferred Deeksha Campus*: —Please choose an option— Deeksha Vedantu, Kanakapura Road, Bengaluru Deeksha Vedantu, Indiranagar, Bengaluru Deeksha Vedantu, Yelahanka, Bengaluru Deeksha Vedantu, Mahalakshmipuram, Bengaluru Vedantu Learning Centre, JP Nagar, Bengaluru Deeksha Vedantu, Kengeri, Bengaluru Deeksha Vedantu, Whitefield, Bengaluru Deeksha Vedantu, Main Campus, Bengaluru Deeksha Vedantu, Thyagarajanagar, Bengaluru Deeksha Vedantu, Thanisandra, Bengaluru Deeksha Vedantu, Vidyanagar, Bengaluru Deeksha Vedantu, Judicial Layout, Bengaluru Deeksha Vedantu, Excellence Batch, Bengaluru Deeksha Vedantu, Nelamangala Boys, Bengaluru Deeksha Vedantu, Nelamangala Girls, Bengaluru Deeksha Vedantu - ES, Somanahalli, Bengaluru Deeksha Vedantu - DSS, Bannerghatta Road, Bengaluru Deeksha Vedantu - AJPS, KR Puram, Bengaluru Deeksha Vedantu, NR Colony, Bengaluru Deeksha Vedantu, Electronic City, Bengaluru Deeksha Vedantu - NEC, Mathikere, Bengaluru Deeksha Vedantu, Bhughathalli, Mysuru Not Sure

Your Preferred Calling Slot*: —Please choose an option— As Soon As Possible Morning (9AM-11AM) Afternoon (11AM-3PM) Evening (3PM-7PM)

Class 6 Maths
Class 6 Science
Class 6 Social Science
Class 6 English
Class 7 Maths
Class 7 Science
Class 7 Social Science
Class 7 English
Class 8 Maths
Class 8 Science
Class 8 Social Science
Class 8 English
Class 9 Maths
Class 9 Science
Class 9 Social Science
Class 9 English
Class 10 Maths
Class 10 Science
Class 10 Social Science
Class 10 English
Class 11 Maths
Class 11 Computer Science (Python)
Class 11 English
Class 12 Maths
Class 12 English
Class 12 Economics
Class 12 Accountancy
Class 12 Physics
Class 12 Chemistry
Class 12 Biology
Class 12 Computer Science (Python)
Class 12 Physical Education
GST and Accounting Course
Excel Course
Tally Course
Finance and CMA Data Course
Payroll Course

Interesting

Learn English
Learn Excel
Learn Tally
Learn GST (Goods and Services Tax)
Learn Accounting and Finance
GST Tax Invoice Format
Accounts Tax Practical
Tally Ledger List
GSTR 2A - JSON to Excel
NCERT Questions
Questions from Inside the chapter
Examples from NCERT Book
Teachoo Questions
MCQs from (Past Year Papers & NCERT Exemplar)
Assertion Reasoning questions (MCQ)
Case Based Questions (MCQ)
Past Year - 1 Mark Questions
Past Year - 2 Mark Questions
Past Year - 3 Mark Questions
Past Year - 5 Mark Questions

Heating Effect of Electric Current

Last updated at April 16, 2024 by Teachoo

googletag.cmd.push(function() { googletag.display('div-gpt-ad-1669298377854-0'); });

What is electric energy.

Electric Energy is product of Electric Power and Time

Electric Energy = Electric power × Time

What are Units of Electrical Energy?

It is Measured in Watt second or Joule

Explanation

Electric Power is measured in Watt and Time in Second

So Electrical Energy-Watt × Hours = Watt Second

Meaning of Heating Effect

When an electric current passes through a conductor (like a high resistance wire)

the conductor becomes hot after some time and produces heat

This is called heating effect of Electric Current

A bulb becomes hot after its use for some time.This is because of heating effect of electric current

When we switch on an electric iron,it becomes hot.This is also because of heating effect of electric current

What causes Heating Effect of Electric Current

Heating Effect happens due to conversion of electric energy into heat energy

We know that battery or cell is a source of electrical energy

Due to chemical reaction in this battery or cell,potential difference is generated

This potential difference causes electrons to flow through circuit

This circuit has resistors which resist flow of current

Work is to be done to overcome this resistance

While doing this work,

This source energy in conductor is dissipated(converted) in resistor as heat energy

What is Formula for Heating Effect of Electric Current

How is heat formula derived.

This is known as Joule's law of heating.

The law implies that

the heat produced in a resistor is

directly proportional to the square of current for a given resistance It means if we double the current,the heat becomes 4 times if we half the current,the heat becomes 1/4 times Hence,more the current,more the heat. Less the current, less heat produced.
directly proportional to resistance for a given current It means if we use a wire made of metal having more resistance (like nichrome wire),it will produce more heat But if we use wire made of metal having less resistance (like copper),it will produce less heat
directly proportional to the time for which the current flows through the resistor It means if we switch on an electric gadget for more time,it will get heated up more But if we use an electric gadget for less time (switch it off after use),it will get less heated

Why do some electric appliances get heated up more (like electric iron) while others get heated up less(like TV)

It is because electric iron has a heating element like high resistance wire which help in converting most of electric energy into heat energy

We know that as per Joule's Law of Heating

Heat is Directly Proportional to the resistance of the wire for a given current

It means if we use a wire made of metal having more resistance (like nichrome wire),it will resist the flow of current and hence it will produce more heat.

Since the resistance of the wires used in electric iron is more than that used Tv, more heat is produced in an electric iron.

Such kind of nichrome wire is used in electric iron which acts as heating element

This converts most of electric energy into heat energy

Different formulas for Heat

We know that,

Heat = Electrical power x time

Hence, the three formulae become

H = (I 2 R)t
H = (V 2 /R)t

Example 12.11 - 100 J of heat is produced each second in a 4 Ω resistance. Find thepotential difference across the resistor.

View Answer

Question 8 - In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be

(a) 5 J (b) 10 J (c) 20 J (d) 30 J

In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are connected in parallel to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be (a) 45 J (b) 20 J (c) 60 J (d) 35 J

How is Heat Formula Derived? We know that Energy = Power × Time Thus, Heat energy due to current = Electric Power × Time H = P × t H = VI × t H = VIt Also, putting V = IR by Ohm’s Law H = VIt H = (IR) × It H = I2Rt Also, putting I = 𝑉/𝑅 by Ohm’s Law H = VIt H = V × 𝑉/𝑅 × It H = 𝑽^𝟐/𝑹t

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo

Hi, it looks like you're using AdBlock :(

Please login to view more pages. it's free :), solve all your doubts with teachoo black.

Current Electricity

Joule's Law

We are aware of the heating impact of electric current. The heat is produced due to the collision electrons in the wire. You might have wondered about the amount of heat generated during the flow of current through a wire and the parameters and conditions it is based upon. To answer all these questions, Joule gave a formula that describes this phenomenon precisely and called it Joule’s Law.

Joule’s Law of Heating

Joule’s law is a mathematical description of the rate at which resistance in a circuit converts electric energy into heat energy.

The English physicist James Prescott discovered that the amount of heat per second that develops in a current-carrying conductor is proportional to the electrical resistance of the wire and the square of the current.

The heat that is generated because of the current flow in an electric wire is described in Joules. The mathematical expression of Joule’s law is as explained below.

Joule’s first law

The joule’s first law shows the relationship between heat produced by flowing electric current through a conductor.

Q = I 2 R T

Q indicates the amount of heat
I show electric current
R is the amount of electric resistance in the conductor
T denotes time
The amount of generated heat is proportional to the wire’s electrical resistance when the current in the circuit and the flow of current is not changed.
The amount of generated heat in a conductor carrying current is proportional to the square of the current flow through the circuit when the electrical resistance and current supply is constant.
The amount of heat produced because of the current flow is proportional to the time of flow when the resistance and current flow is kept constant.

Solved Example

Q1) Calculate the heat energy produced in resistance of 5 Ω when 3 A current flows through it for 2 minutes. The amount of heat produced by the conductor is given by the formula: Q = I 2 R T Substituting the values in the above equation we get Q = 3 2 × 5 × 2 × 60 = 5400 J

Q2) An heater of resistance 300 Ω is connected to the main supply for 30 mins. If 10 A current flows through the filament of the heater then what is the heat produced in the heater? The amount of heat produced by the heater is calculated as follows: Q=I 2 RT substituting the values in the equation, we get Q = 10 2 × 300 × 30 × 60 = 54000000 J or 54 MJ.

To know more about Joule’s law of thermodynamics and solved examples, you can visit us BYJU’S.

Register with BYJU'S & Download Free PDFs

JOULE'S LAW THE HEATING EFFECT OF AN ELECTRIC CURRENT

View the Equipment

I shall lose no time in repeating and extending these experiments, being satisfied that the grand agents of nature are, by the Creator's fiat, indestructible; and that whatever mechanical force is expended, an exact equivalent heat is always obtained.

JOULE, 1843

For a considerable period in the history of physics heat was thought to be some material, but "imponderable," fluid which flowed between hot and cold bodies. The unit of heat (either calorie or British thermal unit) was defined in terms of the rise in temperature produced when heat flowed into unit mass of water.

At the same time in history other workers were concerned with a study of the relationships existing between work done on a system and the mechanical energies of the system. The units of mechanical energy (foot-pound and newton-meter or joule) were naturally defined in terms of the work concept. Even later scientists studying the phenomena associated with electricity elected to use the mechanical units for expressing electrical energy (joules) and power (watts or joules per second).

With the work of Joule (see above) and others, it became apparent that heat was another manifestation of energy and could properly be measured in mechanical units (joules) provided the relationship between those units and the previously established thermal units (calories) could be determined. We write:

where J is called the mechanical equivalent of heat and is expressed in joules per calorie.

In this experiment you are asked to use an electrical calorimeter to determine the numerical value of J. The electrical energy supplied to the calorimeter is given by

where V is the potential difference, I is the current and t is the time.

Since no change of state occurs, we can write the heat energy produced in the calorimeter as

where m represents mass, c the specific heat and D T the temperature change. The summation indicates that you are to write a term, mc D T, for each object which undergoes a temperature change as a result of the electrical energy supplied. Since the assumption is that all electrical energy is converted to heat in an insulated vessel, we should be able to use Equation 1 to determine a value for J.

SPECIFIC OBJECTIVES:

When you have completed this experimental activity you should be able to: (1) construct an electrical circuit from the schematic diagram provided; (2) determine the electrical energy supplied to a system from measured values of V, I, R, t, etc; (3) conduct an experiment to measure the mechanical equivalent of heat; (4) relate the joule or calorie of energy to the kWh unit of electrical energy; and (5) understand the term "water equivalent."

EXPERIMENTAL ACTIVITY:

Prepare a data sheet adequate to record values of V, I, and Temperature as a function of time. You will be making readings at two-minute intervals for about 60 minutes.

Place the thermometer in the stopper so that the bulb will be submerged. A little stopcock lubricant will make it go in easily.

Record in your notebook such data as may be required to determine the heat energy produced in the calorimeter. Think carefully about what you will need to know. The specific heat capacity of the calorimeter and stirrer is 0.215 cal/gm- o C and the water equivalent of the heater element is 3.65 grams.

Use enough cold water from the hall fountain to completely submerge the heating element . The water should be colder than room temperature by 10 o C or more. How will you determine how much water you have?

Connect the circuit a shown in the diagram. Do not plug the power supply into the outlet until your circuit has been approved by your instructor.

ABOVE ALL -- DO NOT TURN ON THE CURRENT UNLESS THE HEATER ELEMENT IS IN WATER.

When all is ready, record the temperature at two-minute intervals for a period of four minutes before turning on the heater. Make all temperature readings as precise as possible -- typically you should be able to read to tenths of a degree if you are careful.

At t=4 minutes, turn on the power supply and immediately adjust the current to 2.0 amperes. You must keep the current at this constant value throughout the experiment. Continue to record the voltage, current, and temperature at two minute intervals until the temperature rises at least 20 o C above the initial temperature. Continue reading the temperature for a period of six to eight minutes after the heating current is turned off.

ANALYSIS OF RESULTS

Plot a graph of temperature as a function of time; include the periods before and after the heating cycle. Explain any non-linear behavior you observe. Was it necessary to make any adjustments during the heating cycle to keep the current constant? If so, explain why.

Calculate the heat energy produced in the calorimeter. Show your work in a neat, well-organized manner. Calculate the magnitude of J and compare with the standard value of 4.19 joule/cal. What is your percent error?

Was there any evident of heat flow into or out of the calorimeter during the pre- or post-heating periods? If so, what was the evidence and how might this affect the results of your experiment? Be specific.
What is meant by the term "water equivalent"?
Why were you cautioned not to turn on the current until the coil was submerged in water?
How many joules of energy have been supplied if your electric meter records one kilowatt-hour? Show your calculation.

FINAL SUMMARY:

In your report summary, include the value you found for J, and indicate what you judge to be the most important source of error in this experiment. What conclusions did you draw about the relationship of thermal units and mechanical energy units?

Return to Table of Contents

IMAGES

VERIFICATION OF JOULE`S LAW
Class 10 ( Derivation of Joule's law of heating )
Heating effect of electric current // Joule's law of heating // Class 10 Physics // Electricity
Joule's Law Of Heating
Joule's law of heating
10S12

VIDEO

#Joule's law of heating I #boardexam2024
Heating effect of electric current and joules law of heating/ class 10th / electricity
Experimental verification of Boyle’s law
Joule's Law of Heating| Heating Effect of Electric Current 💡| class10
Chapter 11 Electricity for Class 10th Joule's Law of Heating and Uses #10thclass (Class -5)
Joules law of heating effect || Joule's law ||Joule's law class 10th || CBSE, ICSE and State board

COMMENTS

Experimental Verification of Joule's Law of Heating - Ask Mattrab
Joule in 1841 experimentally studied the heating effect of electric current. He found that the amount of heat, H produce in a conductor due to the flow of current, (i) is directly proportional to the square of the current flowing through the conductor i.e. H ∝ I 2 (ii) is directly proportional to the resistance across the conductor, H ∝ R
Joule's law of heating Class 10 with Examples - Ox Science
Verification of Joule’s law: The above laws of heating by the electric current can be verified in the laboratory using a joule’s calorimeter. To verify the above laws, heat is generated in a resist; coil R which is enclosed in a copper calorimeter containing water to about two-thirds of its volume.
Derivation of joule's law of heating - BYJU'S
Is joules law of heating effect similar to heating effect of electric current. If no state the difference. Q. The S. I unit of heat is ___________ (Joule/Celsius).
Joule's law of heating — lesson. Science CBSE, Class 10.
Joule’s law of heating states that the heat produced in any resistor is • Directly proportional to the square of the current passing through the resistor. H α I 2 • Directly proportional to the resistance of the resistor. H α R • Directly proportional to the time for which the current is passing through the resistor. H α t
Heating Effect of Electric Current - Applications and Formula
Learn about the heating effect of electric current, Joule’s Law, and its real-world applications. Detailed explanations, FAQs, and practice questions designed for Class 10 CBSE students.
Heating Effect of Electric Current - Class 10 Science Notes ...
We know that as per Joule's Law of Heating. Heat is Directly Proportional to the resistance of the wire for a given current. It means if we use a wire made of metal having more resistance (like nichrome wire),it will resist the flow of current and hence it will produce more heat.
12. Electricity : joules law of heating Science class 10 ...
joule's law of heating: The heat produced in a resistor is directly proportional to the square of current for a given resistance, directly proportional to resistance for a given current, and the time for which the current flows through the resistor. This law is called the joule's law of heating. Joule's law heating is denoted by "H" H = I 2 Rt
Joule's Law Of Heating and Joule's First Law - Physics - BYJU'S
Joule’s law is a mathematical description of the rate at which resistance in a circuit converts electric energy into heat energy. The English physicist James Prescott discovered that the amount of heat per second that develops in a current-carrying conductor is proportional to the electrical resistance of the wire and the square of the current.
JOULE'S LAW THE HEATING EFFECT OF AN ELECTRIC CURRENT
Was there any evident of heat flow into or out of the calorimeter during the pre- or post-heating periods? If so, what was the evidence and how might this affect the results of your experiment? Be specific.
Experimental Verification of Joule's Law of Heating - Toppr
Validity of Joule's Law is verified by the equality of Q1 and Q2. Read formulas, definitions, laws from Heating Effect of Electric Current here. Click here to learn the concepts of Experimental Verification of Joule's Law of Heating from Physics.